1. Field of the Invention
This invention relates to an improved furnace roof construction for an electric arc furnace and particularly, to a dual ring roof structure that is compartmentalized from the standpoint of its refractory tile or block members.
2. Description of the Prior Art
Heretofore, difficulties have been encountered in providing and maintaining the conventional sprung arch type of suspended roof for electric arc furnaces. The heavy compression thrust loading of such a type of roof has the tendency to crush the refractories and cause premature failure. This is especially true in view of the fact that a furnace roof has to be tilted about 45.degree. when the furnace is tapped. In the sprung crown, thin roof areas tend to produce structural weaknesses that will cause the whole roof to collapse. It is also desirable to enable the use of basic brick which can better withstand high temperature and basic slag vapors. However, basic tile or brick has not heretofore been fully satisfactory when used in a roof having the high compression characteristics of a conventional sprung type.
In evaluating the problem, it has been determined that there is a need for an improved type of roof which will enable the maximized cooling of metal structure and, at the same time, which will divide the refractory load in such a manner as to minimize stress and strain on the tile or block members and enable the successful use of so-called basic brick. The difficulty in finding a solution to the problem was found to rest upon the need for proportioning or dividing up the refractory load and in such a manner as to avoid an added appreciable increase in weight of the roof and assure a good operating life from the standpoint of structural metal members employed.